A device described in a patent document 1 and so on is known as a conventional intake device for an internal combustion engine. This intake device is arranged to control an opening area of an intake passage of an intake manifold, and thereby to form a tumble flow within a combustion chamber of the internal combustion engine. The intake device includes a holder mounted on an outlet portion of the intake manifold; and a valve element swingably supported by this holder. A raised seal portion is provided on an outer side surface of the valve element near an upstream side edge portion. A bottom plate is provided on a bottom surface of the holder. The bottom plate constitutes a receiving space for the valve element. The seal portion of the valve element is arranged to be positioned near an end edge of the bottom plate in a valve closing state, and to seal between the valve element and the holder.
However, in the conventional intake device, a clearance remained between the seal portion and the end edge of the bottom plate in the valve closing state becomes relatively large. An intake flow is decreased due to an air leakage flowing through this clearance.